1. Field of the Invention
The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus with the mechanism for ejection recovery procedure.
2. Description of Prior Art
In recent years, a personal computer, a word processor, etc., are widely used. As a recording system for printing out information which was inputted and processed in these apparatus, a variety of recording systems are known, such as a wire dot system, a thermal transfer system and an ink jet system. In these recording systems, recording is made on recording sheets which are relatively transported with respect to the recording head, and there are differences in structure of the recording heads according to those systems.
In the recording heads of the ink jet type, the recording is made by ejecting ink from relatively small orifices. Therefore, in this type recording heads, clogging of the orifices or a deflection of ejected ink may be occurred owing to an increase in ink viscosity due to the evaporation of a solvent, or the dust attached to the orifices and its vicinity and the recording may fail to be made. In order to prevent such a problem, most ink jet recording apparatus are provided with an ejection recovery mechanism for forced discharging the ink in a more viscous state from the recording head by means of pressurizing or sucking it.
In the conventional system, the ejection recovery operation by the forced ink discharge as described above is automatically carried out, when a user operates a recovery switch provided to the ink jet recording apparatus, or just after switch-on of a power source, or every time a constant time elapses from the previous recovery operation.
However, in the case that the user operates the recovery switch, in the conventional system as described above, it is very difficult for the user to decide that the recovery switch should be pressed when the ink jet recording apparatus is in any states. In addition, it is troublesome for the user to operate the recovery switch, and there is a problem that consumption of ink increases when the user would operates the recovery switch for unnecessary recovery procedure.
Further, in the case that the ejection recovery operation is automatically carried out just after switch-on of a power source, unnecessary recovery procedure is often performed when the user often operates a power switch, thus consumption of ink increases.
Further, in the case that the ejection recovery operation is automatically carried out every time a constant time elapses, it is necessary to provide a timer for counting a time interval of the recovery operations. Because the timer must count the elapsed time even when the power source is switched off, it is necessary to provide such as a back-up power source. Life time of the back-up power source is generally shorter than that of the apparatus. It is therefore necessary to exchange the back-up power source for a new one by the user. Accordingly, it is troublesome. In addition, because the optimum time interval greatly depends on the frequency of use of the recording apparatus itself, it is difficult to preset the optimum time interval.
In the above-described manners, the consumption of ink increases as the number of times of the ejection recovery operation increases. Therefore, larger ink tank for the discharged ink is required, and it becomes difficult to make the recording apparatus smaller.
Further, in such an apparatus that an absorber for the discharged ink is used, it is usually necessary to provide a large quantity of absorber. In this case, the whole volume of the absorber becomes larger, because it is necessary to take an acceptable limit into consideration.